[Qemu-devel] Re: [RFC PATCH 01/20] Modify DIRTY_FLAG value and introduce DIRTY_IDX to use as indexes of bit-based phys_ram_dirty.

[Yoshiaki Tamura]

Anthony Liguori wrote:
> Hi,
>
> On 04/21/2010 12:57 AM, Yoshiaki Tamura wrote:
> > Replaces byte-based phys_ram_dirty bitmap with four (MASTER, VGA,
> > CODE, MIGRATION) bit-based phys_ram_dirty bitmap. On allocation, it
> > sets all bits in the bitmap. It uses ffs() to convert DIRTY_FLAG to
> > DIRTY_IDX.
> >
> > Modifies wrapper functions for byte-based phys_ram_dirty bitmap to
> > bit-based phys_ram_dirty bitmap. MASTER works as a buffer, and upon
> > get_diry() or get_dirty_flags(), it calls
> > cpu_physical_memory_sync_master() to update VGA and MIGRATION.
>
> Why use an additional bitmap for MASTER instead of just updating the
> VGA, CODE, and MIGRATION bitmaps together?

This way we don't have to think whether we should update VGA or MIGRATION. 
IIRC, we had this discussion on upstream before with Avi?

http://www.mail-archive.com/address@hidden/msg30728.html

BTW, I also have the following TODO list regarding dirty bitmap.

1. Allocate vga and migration dirty bitmap dynamically.
2. Separate CODE and the other dirty bitmaps functions.

> Regards,
>
> Anthony Liguori
>
> > Replaces direct phys_ram_dirty access with wrapper functions to
> > prevent direct access to the phys_ram_dirty bitmap.
> >
> > Signed-off-by: Yoshiaki Tamura<address@hidden>
> > Signed-off-by: OHMURA Kei<address@hidden>
> > ---
> > cpu-all.h | 130
> > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
> > exec.c | 60 ++++++++++++++--------------
> > 2 files changed, 152 insertions(+), 38 deletions(-)
> >
> > diff --git a/cpu-all.h b/cpu-all.h
> > index 51effc0..3f8762d 100644
> > --- a/cpu-all.h
> > +++ b/cpu-all.h
> > @@ -37,6 +37,9 @@
> >
> > #include "softfloat.h"
> >
> > +/* to use ffs in flag_to_idx() */
> > +#include<strings.h>
> > +
> > #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
> > #define BSWAP_NEEDED
> > #endif
> > @@ -846,7 +849,6 @@ int cpu_str_to_log_mask(const char *str);
> > /* memory API */
> >
> > extern int phys_ram_fd;
> > -extern uint8_t *phys_ram_dirty;
> > extern ram_addr_t ram_size;
> > extern ram_addr_t last_ram_offset;
> > extern uint8_t *bios_mem;
> > @@ -869,28 +871,140 @@ extern uint8_t *bios_mem;
> > /* Set if TLB entry is an IO callback. */
> > #define TLB_MMIO (1<< 5)
> >
> > +/* Use DIRTY_IDX as indexes of bit-based phys_ram_dirty. */
> > +#define MASTER_DIRTY_IDX 0
> > +#define VGA_DIRTY_IDX 1
> > +#define CODE_DIRTY_IDX 2
> > +#define MIGRATION_DIRTY_IDX 3
> > +#define NUM_DIRTY_IDX 4
> > +
> > +#define MASTER_DIRTY_FLAG (1<< MASTER_DIRTY_IDX)
> > +#define VGA_DIRTY_FLAG (1<< VGA_DIRTY_IDX)
> > +#define CODE_DIRTY_FLAG (1<< CODE_DIRTY_IDX)
> > +#define MIGRATION_DIRTY_FLAG (1<< MIGRATION_DIRTY_IDX)
> > +
> > +extern unsigned long *phys_ram_dirty[NUM_DIRTY_IDX];
> > +
> > +static inline int dirty_flag_to_idx(int flag)
> > +{
> > + return ffs(flag) - 1;
> > +}
> > +
> > +static inline int dirty_idx_to_flag(int idx)
> > +{
> > + return 1<< idx;
> > +}
> > +
> > int cpu_memory_rw_debug(CPUState *env, target_ulong addr,
> > uint8_t *buf, int len, int is_write);
> >
> > -#define VGA_DIRTY_FLAG 0x01
> > -#define CODE_DIRTY_FLAG 0x02
> > -#define MIGRATION_DIRTY_FLAG 0x08
> > -
> > /* read dirty bit (return 0 or 1) */
> > static inline int cpu_physical_memory_is_dirty(ram_addr_t addr)
> > {
> > - return phys_ram_dirty[addr>> TARGET_PAGE_BITS] == 0xff;
> > + unsigned long mask;
> > + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
> > + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
> > +
> > + mask = 1UL<< offset;
> > + return (phys_ram_dirty[MASTER_DIRTY_IDX][index]& mask) == mask;
> > +}
> > +
> > +static inline void cpu_physical_memory_sync_master(ram_addr_t index)
> > +{
> > + if (phys_ram_dirty[MASTER_DIRTY_IDX][index]) {
> > + phys_ram_dirty[VGA_DIRTY_IDX][index]
> > + |= phys_ram_dirty[MASTER_DIRTY_IDX][index];
> > + phys_ram_dirty[MIGRATION_DIRTY_IDX][index]
> > + |= phys_ram_dirty[MASTER_DIRTY_IDX][index];
> > + phys_ram_dirty[MASTER_DIRTY_IDX][index] = 0UL;
> > + }
> > +}
> > +
> > +static inline int cpu_physical_memory_get_dirty_flags(ram_addr_t addr)
> > +{
> > + unsigned long mask;
> > + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
> > + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
> > + int ret = 0, i;
> > +
> > + mask = 1UL<< offset;
> > + cpu_physical_memory_sync_master(index);
> > +
> > + for (i = VGA_DIRTY_IDX; i<= MIGRATION_DIRTY_IDX; i++) {
> > + if (phys_ram_dirty[i][index]& mask) {
> > + ret |= dirty_idx_to_flag(i);
> > + }
> > + }
> > +
> > + return ret;
> > +}
> > +
> > +static inline int cpu_physical_memory_get_dirty_idx(ram_addr_t addr,
> > + int dirty_idx)
> > +{
> > + unsigned long mask;
> > + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
> > + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
> > +
> > + mask = 1UL<< offset;
> > + cpu_physical_memory_sync_master(index);
> > + return (phys_ram_dirty[dirty_idx][index]& mask) == mask;
> > }
> >
> > static inline int cpu_physical_memory_get_dirty(ram_addr_t addr,
> > int dirty_flags)
> > {
> > - return phys_ram_dirty[addr>> TARGET_PAGE_BITS]& dirty_flags;
> > + return cpu_physical_memory_get_dirty_idx(addr,
> > + dirty_flag_to_idx(dirty_flags));
> > }
> >
> > static inline void cpu_physical_memory_set_dirty(ram_addr_t addr)
> > {
> > - phys_ram_dirty[addr>> TARGET_PAGE_BITS] = 0xff;
> > + unsigned long mask;
> > + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
> > + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
> > +
> > + mask = 1UL<< offset;
> > + phys_ram_dirty[MASTER_DIRTY_IDX][index] |= mask;
> > +}
> > +
> > +static inline void cpu_physical_memory_set_dirty_range(ram_addr_t addr,
> > + unsigned long mask)
> > +{
> > + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
> > +
> > + phys_ram_dirty[MASTER_DIRTY_IDX][index] |= mask;
> > +}
> > +
> > +static inline void cpu_physical_memory_set_dirty_flags(ram_addr_t addr,
> > + int dirty_flags)
> > +{
> > + unsigned long mask;
> > + ram_addr_t index = (addr>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
> > + int offset = (addr>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
> > +
> > + mask = 1UL<< offset;
> > + phys_ram_dirty[MASTER_DIRTY_IDX][index] |= mask;
> > +
> > + if (dirty_flags& CODE_DIRTY_FLAG) {
> > + phys_ram_dirty[CODE_DIRTY_IDX][index] |= mask;
> > + }
> > +}
> > +
> > +static inline void cpu_physical_memory_mask_dirty_range(ram_addr_t
> > start,
> > + unsigned long length,
> > + int dirty_flags)
> > +{
> > + ram_addr_t addr = start, index;
> > + unsigned long mask;
> > + int offset, i;
> > +
> > + for (i = 0; i< length; i += TARGET_PAGE_SIZE) {
> > + index = ((addr + i)>> TARGET_PAGE_BITS) / HOST_LONG_BITS;
> > + offset = ((addr + i)>> TARGET_PAGE_BITS)& (HOST_LONG_BITS - 1);
> > + mask = ~(1UL<< offset);
> > + phys_ram_dirty[dirty_flag_to_idx(dirty_flags)][index]&= mask;
> > + }
> > }
> >
> > void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t end,
> > diff --git a/exec.c b/exec.c
> > index b647512..bf8d703 100644
> > --- a/exec.c
> > +++ b/exec.c
> > @@ -119,7 +119,7 @@ uint8_t *code_gen_ptr;
> >
> > #if !defined(CONFIG_USER_ONLY)
> > int phys_ram_fd;
> > -uint8_t *phys_ram_dirty;
> > +unsigned long *phys_ram_dirty[NUM_DIRTY_IDX];
> > uint8_t *bios_mem;
> > static int in_migration;
> >
> > @@ -1947,7 +1947,7 @@ static void tlb_protect_code(ram_addr_t ram_addr)
> > static void tlb_unprotect_code_phys(CPUState *env, ram_addr_t ram_addr,
> > target_ulong vaddr)
> > {
> > - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] |= CODE_DIRTY_FLAG;
> > + cpu_physical_memory_set_dirty_flags(ram_addr, CODE_DIRTY_FLAG);
> > }
> >
> > static inline void tlb_reset_dirty_range(CPUTLBEntry *tlb_entry,
> > @@ -1968,8 +1968,7 @@ void cpu_physical_memory_reset_dirty(ram_addr_t
> > start, ram_addr_t end,
> > {
> > CPUState *env;
> > unsigned long length, start1;
> > - int i, mask, len;
> > - uint8_t *p;
> > + int i;
> >
> > start&= TARGET_PAGE_MASK;
> > end = TARGET_PAGE_ALIGN(end);
> > @@ -1977,11 +1976,7 @@ void cpu_physical_memory_reset_dirty(ram_addr_t
> > start, ram_addr_t end,
> > length = end - start;
> > if (length == 0)
> > return;
> > - len = length>> TARGET_PAGE_BITS;
> > - mask = ~dirty_flags;
> > - p = phys_ram_dirty + (start>> TARGET_PAGE_BITS);
> > - for(i = 0; i< len; i++)
> > - p[i]&= mask;
> > + cpu_physical_memory_mask_dirty_range(start, length, dirty_flags);
> >
> > /* we modify the TLB cache so that the dirty bit will be set again
> > when accessing the range */
> > @@ -2643,6 +2638,7 @@ extern const char *mem_path;
> > ram_addr_t qemu_ram_alloc(ram_addr_t size)
> > {
> > RAMBlock *new_block;
> > + int i;
> >
> > size = TARGET_PAGE_ALIGN(size);
> > new_block = qemu_malloc(sizeof(*new_block));
> > @@ -2667,10 +2663,14 @@ ram_addr_t qemu_ram_alloc(ram_addr_t size)
> > new_block->next = ram_blocks;
> > ram_blocks = new_block;
> >
> > - phys_ram_dirty = qemu_realloc(phys_ram_dirty,
> > - (last_ram_offset + size)>> TARGET_PAGE_BITS);
> > - memset(phys_ram_dirty + (last_ram_offset>> TARGET_PAGE_BITS),
> > - 0xff, size>> TARGET_PAGE_BITS);
> > + for (i = MASTER_DIRTY_IDX; i< NUM_DIRTY_IDX; i++) {
> > + phys_ram_dirty[i]
> > + = qemu_realloc(phys_ram_dirty[i],
> > + BITMAP_SIZE(last_ram_offset + size));
> > + memset((uint8_t *)phys_ram_dirty[i] + BITMAP_SIZE(last_ram_offset),
> > + 0xff, BITMAP_SIZE(last_ram_offset + size)
> > + - BITMAP_SIZE(last_ram_offset));
> > + }
> >
> > last_ram_offset += size;
> >
> > @@ -2833,16 +2833,16 @@ static void notdirty_mem_writeb(void *opaque,
> > target_phys_addr_t ram_addr,
> > uint32_t val)
> > {
> > int dirty_flags;
> > - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
> > + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
> > if (!(dirty_flags& CODE_DIRTY_FLAG)) {
> > #if !defined(CONFIG_USER_ONLY)
> > tb_invalidate_phys_page_fast(ram_addr, 1);
> > - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
> > + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
> > #endif
> > }
> > stb_p(qemu_get_ram_ptr(ram_addr), val);
> > dirty_flags |= (0xff& ~CODE_DIRTY_FLAG);
> > - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] = dirty_flags;
> > + cpu_physical_memory_set_dirty_flags(ram_addr, dirty_flags);
> > /* we remove the notdirty callback only if the code has been
> > flushed */
> > if (dirty_flags == 0xff)
> > @@ -2853,16 +2853,16 @@ static void notdirty_mem_writew(void *opaque,
> > target_phys_addr_t ram_addr,
> > uint32_t val)
> > {
> > int dirty_flags;
> > - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
> > + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
> > if (!(dirty_flags& CODE_DIRTY_FLAG)) {
> > #if !defined(CONFIG_USER_ONLY)
> > tb_invalidate_phys_page_fast(ram_addr, 2);
> > - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
> > + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
> > #endif
> > }
> > stw_p(qemu_get_ram_ptr(ram_addr), val);
> > dirty_flags |= (0xff& ~CODE_DIRTY_FLAG);
> > - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] = dirty_flags;
> > + cpu_physical_memory_set_dirty_flags(ram_addr, dirty_flags);
> > /* we remove the notdirty callback only if the code has been
> > flushed */
> > if (dirty_flags == 0xff)
> > @@ -2873,16 +2873,16 @@ static void notdirty_mem_writel(void *opaque,
> > target_phys_addr_t ram_addr,
> > uint32_t val)
> > {
> > int dirty_flags;
> > - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
> > + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
> > if (!(dirty_flags& CODE_DIRTY_FLAG)) {
> > #if !defined(CONFIG_USER_ONLY)
> > tb_invalidate_phys_page_fast(ram_addr, 4);
> > - dirty_flags = phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS];
> > + dirty_flags = cpu_physical_memory_get_dirty_flags(ram_addr);
> > #endif
> > }
> > stl_p(qemu_get_ram_ptr(ram_addr), val);
> > dirty_flags |= (0xff& ~CODE_DIRTY_FLAG);
> > - phys_ram_dirty[ram_addr>> TARGET_PAGE_BITS] = dirty_flags;
> > + cpu_physical_memory_set_dirty_flags(ram_addr, dirty_flags);
> > /* we remove the notdirty callback only if the code has been
> > flushed */
> > if (dirty_flags == 0xff)
> > @@ -3334,8 +3334,8 @@ void cpu_physical_memory_rw(target_phys_addr_t
> > addr, uint8_t *buf,
> > /* invalidate code */
> > tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
> > /* set dirty bit */
> > - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
> > - (0xff& ~CODE_DIRTY_FLAG);
> > + cpu_physical_memory_set_dirty_flags(
> > + addr1, (0xff& ~CODE_DIRTY_FLAG));
> > }
> > /* qemu doesn't execute guest code directly, but kvm does
> > therefore flush instruction caches */
> > @@ -3548,8 +3548,8 @@ void cpu_physical_memory_unmap(void *buffer,
> > target_phys_addr_t len,
> > /* invalidate code */
> > tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
> > /* set dirty bit */
> > - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
> > - (0xff& ~CODE_DIRTY_FLAG);
> > + cpu_physical_memory_set_dirty_flags(
> > + addr1, (0xff& ~CODE_DIRTY_FLAG));
> > }
> > addr1 += l;
> > access_len -= l;
> > @@ -3685,8 +3685,8 @@ void stl_phys_notdirty(target_phys_addr_t addr,
> > uint32_t val)
> > /* invalidate code */
> > tb_invalidate_phys_page_range(addr1, addr1 + 4, 0);
> > /* set dirty bit */
> > - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
> > - (0xff& ~CODE_DIRTY_FLAG);
> > + cpu_physical_memory_set_dirty_flags(
> > + addr1, (0xff& ~CODE_DIRTY_FLAG));
> > }
> > }
> > }
> > @@ -3754,8 +3754,8 @@ void stl_phys(target_phys_addr_t addr, uint32_t
> > val)
> > /* invalidate code */
> > tb_invalidate_phys_page_range(addr1, addr1 + 4, 0);
> > /* set dirty bit */
> > - phys_ram_dirty[addr1>> TARGET_PAGE_BITS] |=
> > - (0xff& ~CODE_DIRTY_FLAG);
> > + cpu_physical_memory_set_dirty_flags(addr1,
> > + (0xff& ~CODE_DIRTY_FLAG));
> > }
> > }
> > }